The first galaxy was discovered without dark matter

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Similarly, MOND theorists expect to find the most significant observable effects of their modified laws in less massive galaxies like NGC 1052-DF2, and lesser effects in more-massive galaxies.

For the first time ever, astronomers have detected a galaxy located millions of light-years from Earth with nearly no dark matter at all. "For decades, we thought that galaxies start their lives as blobs of dark matter".

"I spent an hour just staring at this image", lead researcher Pieter van Dokkum of Yale University says as he recalls first seeing the Hubble image of NGC 1052-DF2. "It is literally a see-through galaxy", he added.

Now, while using a new telescope, known as the Dragonfly Telescope Array, astronomers looking for faint, hard-to-find objects out in the universe, have found what they call an "Ultra-Diffuse Galaxy", named NGC1052-DF2 (DF2 for short), which has them scratching their collective heads.

Now, it seems that at least some galaxies exist with many stars and gases, and little dark matter.

"The absence of dark matter from a small patch of sky might appear to be a non-problem, given that astronomers have never directly observed dark matter anywhere", says The Guardian.

The galaxy was studied by many telescopes (Jemini and Kek Hawaii, Space Hubble, etc.) to cross-check the results.

Not all galaxies are made the same when it comes to dark matter.

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Before, scientists believed that galaxies were composed of stars, gases and dark matter, all mixed together.

Paradoxically, the authors said the discovery of a galaxy without dark matter counts as evidence that it probably does exist. NGC 1052-DF2 is considered to be some 10 billion years old.

The discovery of the galaxy without dark matter, according to van Dokkum, "was completely unexpected". Luckily, their studies might be given an early boost as Hubble images of 23 other ultra-diffuse galaxies seem to suggest that three of them are similar to NGC 1052-DF2.

Most paths to explaining NGC 1052-DF2's formation implicate its galactic neighbors.

Andrew Pontzen, a cosmologist at University College London who was not involved in the work, said: "Alternative gravity theories tend to be tuned to reproduce typical galaxies, which means they can struggle to account for anything new or unusual".

The obvious question is how you end up with a galaxy like NGC1052-DF2. But how it formed is a complete mystery. One idea is that the gas got concentrated as it was being ejected from a galaxy merger; another is that it formed from matter spewed out by quasars.

The researchers believe that the points are probably globular clusters, tight balls of stars often found in the outer reaches of galaxies. Imaging them enabled the research study group to establish their activities orbiting the galaxy, which could, consequently, give an action of the quantity of mass that is associated with maintaining the things in position. Indeed, if the mass of DF2 is equal to the sum of the masses of its stars, gas, and dust, it's because it contains no or nearly no dark matter! Because there's some regular issue right here, any kind of variation of customized gravity would certainly have that issue generate dark-matter-like impacts.

In fact, the best fit for the motion of the globular clusters is a galaxy with no dark matter at all, although the uncertainties are high enough that there could be equal amounts of matter and dark matter present. Simply put, the velocity at which clusters orbit a galaxy is related to the amount of matter-normal or dark-that a galaxy contains. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope.